I agree with those that say do a full winterize with pink antifreeze through each fixture, hot and cold and in the traps. "Blowing Out" has its place, I do it after each spring trip for those nights where the temps dip down to ~30f overnight low (and maybe 55 daytime.) You are talking about 10f and I assume possibly not warming above freezing during the day. Unless you are planning to leave the heat on, blowing out alone won't help you, you need a full winterize with the pink stuff in my opinion.
You shouldn't need to pour it in the fresh tank if you have a place to hook up to winterize. Make sure to bypass your water heater. I can do my whole rig with 2 gallons. Don't forget the outside shower and low point drains.
